ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

3pEA5. Characterizing the performance of piezoelectric ceramic as a
function of stress, electric field, and thermal history.

R. Lowell Smith

Alan V. Bray

Texas Res. Inst., 9063 Bee Caves Rd., Austin, TX 78733

The relatively recent development of large flextensional and other
low-frequency, high-power transducers has stimulated renewed interest in the
performance of piezoelectric ceramic under conditions of high stress and
electric field. This paper addresses the development of special fixturing for
the assembly and testing of structures emulating the use of PZT-8 material in
high-power projectors. The test fixtures themselves are Tonpilz oscillators.
Using a system of four tie rods, axial loads as high as 2.2x10[sup 5] N (50 000
lbf) can be applied. The tie rods are fitted with strain gauges so that load
can be monitored as often as desired during the course of aging and stress and
electrical drive sensitivity studies. Initially data were acquired for combined
static and dynamic stress in a controlled thermal environment. The performance
characteristics of the piezoelectric ceramic are inferred from electrical
admittance measurements. Providing for the incorporation of extensometers and
closed-loop control of axial stress allows the fixtures to be used for a number
of broader applications such as measurement of the viscoelastic properties of
ceramic. [Work supported by SPAWAR.]